Right, I've expanded and started a silicon mine in Three Worlds (not Rings!). I also bought another Express, and deposited 60,000 in its bank account to cover material costs.

As I've been pumping tonnes of energy cells into the game for a while now it's quite hard to find lots of cheap sources of them. So I wanted to get them for cost at my own SPP (ie for approx 12c), however it's not possible by default to set a high sell price and have your own ships buy for another price.

However I found this link to a modification of the BuyWare script here (which also has loads of useful information). This allows you to control the number of trips (-1 for infinite) and the price to pay if it's a station you own. Really useful.

btw You need to enable the in-game editor to follow the instructions for that mod. While in space (and with no menus open) type 'Thereshallbewings' (case-sensitive) to enable the in-game script editor. Then S -> C -> S to access.